1. Field of the Invention
The present invention relates generally to an improved tool for finishing the interior wall of a cylindrical bore, and more particularly to a combined skiving and roller burnishing tool which is capable of finishing very long cylinders with minimum deviation from a truly straight cylindrical wall.
2. Description of the Prior Art
In order to prepare the interior wall of a cylinder, such as a pneumatic or hydraulic cylinder, to the close tolerances necessary for proper operation, the cylinder will first be cut to the final diameter by a "skiving" tool and the resulting rough surface then finished with a "burnishing" tool. Often, the skiving and burnishing operations will be performed simultaneously by a combined skiving and roller burnishing tool, which tools are commercially available.
Such a combined skiving and roller burnishing tool will include a cutting blade at its forward end to cut the interior of the cylinder to its approximate final diameter and a plurality of rollers spaced a short distance behind the cutting blade. By rotating the tool and moving it forward through the rough cut cylindrical bore, the cylinder is cut to its final size and finished in a single operation.
While the combined skiving and roller burnishing tools of the type just described are generally functional and provide high quality finished cylinders, their use on very long cylindrical bores can be problematic. It will be appreciated that when cutting and finishing a cylinder, it is desirable that only the cutting tool and the burnishing rollers be in contact with the interior cylindrical wall. Contact between any other portions of the tool and the cylindrical wall can scratch or mar the surface which, of course, is undesirable. Such limited contact between the tool and the cylindrical wall, however, can lead to misalignment of the tool, particularly when very long bores are being finished. The tools are mounted on drive members and the long drive members required for very long bores will not be completely rigid. Any bending in the drive member can cause the cutting blade to oscillate or wobble, causing minor undulations in the finished cylindrical wall. While such undulations may be very small, they may often exceed the close tolerances required for critical applications.
It would thus be desirable to provide a skiving and roller burnishing tool which will remain axially aligned with the cylinder despite bending in the associated drive member and is capable of finishing relatively long cylindrical bores to within very close tolerances.